The purpose of this paper is to propose an empirical relationship for estimating Japan Meteorological Agency instrumental seismic intensity from ground motion parameters such as PGA, PGV and the product of PGA and PGV. Using the strong ground-motion records during recent major earthquakes from the Hyogo-ken Nanbu Earthquake in 1995 to the Iwate-Miyagi Nairiku Earthquake in 2008, we examine the effect of earthquake magnitudes on the relationship. We also compare two regression models, i.e., simple liner regression model and second-order polynominal regression model, to determine which of the models is fitted the actual relationship better in the higher intensity range such as intensity 5 upper or more by using the Akaike's Information Criterion (AIC). Considering these results, we develop the empirical relationship for estimating instrumental seismic intensity from ground motion parameters and earthquake magnitude.

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The strong motion accelerogram observed at Hachinohe harbor during the 1968 Tokachi-oki earthquake is re-digitized and examined because of frequent use of the record in seismic design of high-rise buildings. After the data processing, the digitized data are obtained for 234 seconds. The data indicate that 1) the spectra are almost same as those of the previous digital data, but not at periods longer than 5 seconds, 2) the duration of acceleration is about 70 seconds, but longer for velocity and displacement, and 3) the combination of the S-waves and basin-induced surface waves may produce the larger amplitudes at longer periods.

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This study evaluates and compares seismic risks associated with inland crustal earthquakes in Japan on the basis of published data available on the Japan Seismic Hazard Information Station (J-SHIS). First, taking account of prediction uncertainty of the attenuation law of seismic intensity, the evaluation method for population exposure (PEX) to seismic intensity is presented. The method is applied to 333 seismic events potentially caused by main active faults (154 cases) and other active faults (179 cases). The relationship between population exposure and the probability of occurrence of seismic events ("P-PEX relation") and the resultant seismic risk curves are obtained. Generalized risk index which incorporates the effects of focusing on urgency (probability) or significance (PEX) is defined, producing various risk rankings of active faults.

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This study aims to assess the distribution characteristics of seismic ground motion intensities in the Kanto region of Japan based on the seismic records observed by several organizations' networks. The spatial distribution characteristics of seismic ground motion intensities are extracted as the difference between the arranged observation data compiled from these networks and the standard values derived from empirical models. In this study, three indices were used to represent the seismic ground motion intensities: peak ground acceleration, peak ground velocity, and the Japan Meteorological Agency (JMA) seismic intensity. The results of investigation suggest that the distribution characteristics of seismic ground motion intensities based on the peak ground velocity and JMA seismic intensity are largely affected by the site amplification factors of the subsurface layers. The distribution characteristics of the seismic ground motion intensities may be influenced not only by the site amplification of subsurface layers, but also by the effect of the seismic source and/or path characteristics.

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This paper proposes a basic model for evaluating economic impacts on industrial sectors under the conditions that multiple infrastructures are simultaneously damaged during the earthquake disasters. Especially, focusing on the available economic data developed in the smallest spatial scale in Japan (small area statistics), economic loss estimation model based on the small area statistics and its applicability are investigated on. In the detail, a loss estimation framework, utilizing survey results on firms' activities under electricity, water and gas disruptions, and route choice models in Transportation Engineering, are applied to the case of 2004 Mid-Niigata Earthquake.

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In the Tokyo metropolitan area, high-rise buildings will suffer strong ground motions in near future. In order to estimate damage of the buildings and to carry out counter measures for reducing the damage, it is necessary to know the accurate vibration characteristics of the buildings during the strong ground motions. The purpose of the paper is to investigate vibration characteristics of the Shinjuku Campus building of the 28th floors in Shinjuku, Tokyo, which is a steel structure of moment frames with143 m height. First, we constructed a 3D moment frame model and compared vibration characteristics, such as the natural periods and the corresponding mode shapes, with those obtained by microtremors measurements and manpower excitations. We obtained excellent agreements between them. Second, we compared the observed building response during earthquakes with those of the simulations; we again obtained agreements.

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We discussed stochastic properties of the spatial auto-correlation(SPAC) coefficients for microtremor data which are observed simultaneously at two sites. Usually, the SPAC method can provide the phase velocities using the data observed simultaneously on circular array with four or seven sites. The method, however, suggests analytically the possibility that we can estimate the phase velocities using only the data observed simultaneously at two sites. To clarify the limitation of this idea, some mathematical analyses are performed and stochastic properties of the SPAC coefficients are derived. Furthermore, some real data of microtremors are applied to the above analytical results and the validity is discussed.

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